Abstract: Previous studies have shown that the effect of emotional distractor on working memory (WM) is mixed. In neuroimaging studies, the activity of fronto-parietal cortex related to WM is reduced when emotional distractor presented. In EEG studies, the parietal P3 component is related to WM process. However, the acute stress effect on WM related P3 component is still unclear. To this end, we conducted an EEG study by implementing an working memory paradigm to examine how the acute stress affects ongoing working memory processing. In this paradigm, acute stress/neutral movie clips were used to induce stress status. Participants performed an N-back task with sequentially presented number, in which they were asked to identify whether the current number is identical with the one presented two trials before (i.e., 2-back, higher WM load) or with 1 (0-back, lower WM load). The heart beats and subjective feeling were recorded for emotional mood measurement. The heart beats and negative emotional feeling were significantly higher in the stress group compare to neutral group, which suggests successfully acute stress induction. The amplitude of parietal P3 was significantly bigger in the 0-back condition than in the 2-back condition. These results were consistent with previous EEG studies using N-back task, which have shown that the smaller P3 in high WM load condition. Furthermore, compare to the neutral condition, the acute stress has stronger effect on P3 in 0-back task than in 2-back task. These results can easily explained by the recently proposed dual competition model positing that emotional and cognitive processes, when operating simultaneously, compete with each other for limited neural resources. Specifically, processing of emotional stimuli may interfere with ongoing cognitive processes when cognitive resources are not entirely devoted to goal-directed processing under a lower task demanding condition, such as during the 0-back task in our study. When more resources are required to achieve goal-directed behavior such as in the 2-back WM task here, however, the interference effect is attenuated due to the suppression of stress processing. Together, these results suggest that P3 is a reliable marker for WM load in n-back task. Furthermore, these results provide direct evidence for the dual competition model.

Key words: acute stress, working memory, P3, dual competition model

摘要： 情绪对工作记忆中的信息维持和提取有显著影响，但急性应激如何影响工作记忆的中央执行功能还不清楚。采用电影片断诱发被试的急性应激或中性状态之后，让其完成数字N-back任务并同时记录脑电。结果发现，低负荷工作记忆诱发的P3显著大于高负荷工作记忆；与中性状态相比，急性应激在0-back任务中对P3 的影响显著大于2-back任务。这些结果表明急性应激对工作记忆的影响取决于工作记忆负荷，支持了双竞争理论模型。

关键词: 急性应激, 工作记忆, P3, 双竞争模型